Composite SBS modified asphalt and preparation method thereof

The invention provides composite SBS (styrene butadiene styrene) modified asphalt and a preparation method thereof. The composite SBS modified asphalt is prepared from Shell 70 # A-grade matrix asphalt, SBS (styrene-butadiene-styrene block copolymer), aromatic hydrocarbon thickened oil, sulfur and 2-(2 '-hydroxy-3', 5 '-di-tert-butylphenyl)-5-chlorobenzotriazole. According to the invention, the asphalt is modified by using two SBS (Styrene Butadiene Styrene) of YH791 and YH801, the particle size of polymer particles is processed to be less than 10 [mu] m in the shearing process by utilizing the structural characteristics of the two modifiers, and the polymer generates a physical crosslinking effect through a micro-agglomeration effect in the development and stirring process; aromatic hydrocarbon thickened oil is utilized to soften asphalt, the compatibility of the two modifiers with the asphalt after mixing is improved, sulfur is utilized to react C = C bonds or alpha hydrogen in a polymer PB section to form